1. Field of the Invention
The present invention relates to a dielectric layer and a thin film transistor, and more particularly, to a high-quality dielectric layer and a thin film transistor having the dielectric layer.
2. Description of Related Art
The thin film transistor liquid crystal display (TFT-LCD) has become the mainstream among various flat panel displays because of its superior characteristics such as high resolution, good space usage, low power consumption and free of radiation. Especially, when fabricating a TFT-LCD, a superior film-forming technology of a gate insulation film can enhance the electrical characteristics of the TFT.
In a conventional fabricating process of the polysilicon TFT, an amorphous silicon (a-Si) layer is re-crystallized as a polysilicon layer after a laser annealing process. Afterwards, a gate insulation film is formed to cover the polysilicon layer. Next, a gate is formed on the gate insulation film over the polysilicon layer. In the polysilicon TFT, both the polysilicon layer served as device channel layers and the gate insulation film are important factors which affect the electrical characteristics. Especially after a subsequent ion implantation process, grain boundary traps, traps of an oxide layer, and interface trap states between the polysilicon layer and the gate insulation layer increase, and dangling bonds are generated in the gate insulation film. As a result, probability of charged particles being confined within the gate insulation layer are increased, which in turn deteriorates the electrical characteristics.
In view of the above-mentioned, it becomes rather difficult to further improve the electrical characteristics of the polysilicon TFT during the conventional polysilicon TFT fabricating process.